Submission #197412

#	Time	Username	Problem	Language	Result	Execution time	Memory
197412		abacaba	Aliens (IOI16_aliens)	C++14	25 / 100	26 ms	10232 KiB

aliens

#include <iostream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <cstring>
#include <chrono>
#include <vector>
#include <map>
#include <random>
#include <set>
#include <algorithm> 
#include <math.h>
#include <cstdio>
#include <stdio.h>
#include <queue>
#include <bitset>
#include <cstdlib>
#include <deque>
#include <cassert>
#include <stack>
using namespace std;

#define mp make_pair
#define f first
#define se second
#define pb push_back
#define ppb pop_back
#define ll long long
#define ull unsigned long long
#define cntbit(x) __builtin_popcount(x)
#define endl '\n'
#define uset unordered_set
#define umap unordered_map
#define all(x) x.begin(), x.end()
#define pii pair<int, int>
#define ld long double
#define pll pair<long long, long long>

const int mod = 1e9 + 7;
const ll inf = 2e15;
const int N = 5e2 + 15;
ll dp[N][N];
int l[N], r[N];
int ord[N];
vector <pii> tmp;
ll val[N];

inline ll sq(ll x) {
    return x * x;
}

inline void Min(ll &a, ll b) {
    a = min(a, b);
}

struct line {
    int k;
    ll b;
    line(int k, ll b) : k(k), b(b) {}
    inline ll get(int x) {
        return (ll)k * x + b;
    }
    inline ld intersect(line nw) {
        return (ld)(b - nw.b) / (nw.k - k);
    }
};

vector <line> hull;
int ptr;

inline bool bad(line a, line b, line c) {
    return (a.b - c.b) * (c.k - b.k) >= (c.k - a.k) * (b.b - c.b);
}

inline void add(line nw) {
    while(hull.size() > 1 && bad(hull[hull.size() - 2], hull.back(), nw))
        hull.ppb();
    hull.pb(nw);
}

inline ll get(int x) {
    ptr = min(ptr, (int)hull.size() - 1);
    while(ptr + 1 < hull.size() && hull[ptr].get(x) >= hull[ptr + 1].get(x))
        ++ptr;
    return hull[ptr].get(x);
}

ll take_photos(int n, int m, int k, std::vector<int> row, std::vector<int> col) {
    for(int i = 0; i < n; ++i) {
        l[i+1] = min(row[i], col[i]) + 1;
        r[i+1] = max(row[i], col[i]) + 1;
        ord[i+1] = i+1;
    }
    sort(ord + 1, ord + 1 + n, [&](int x, int y) {
        return mp(l[x], -r[x]) < mp(l[y], -r[y]);
    });
    for(int i = 1; i <= n; ++i)
        if(tmp.empty() || !(tmp.back().f <= l[ord[i]] && tmp.back().se >= r[ord[i]]))
            tmp.pb(mp(l[ord[i]], r[ord[i]]));
    n = tmp.size();
    for(int i = 1; i <= n; ++i) {
        l[i] = tmp[i-1].f, r[i] = tmp[i-1].se;
        val[i] = sq(max(0, r[i-1] - l[i] + 1));
    }
    for(int i = 0; i < N; ++i)
        for(int j = 0; j < N; ++j)
            dp[i][j] = inf;
    dp[0][0] = 0;
    for(int t = 1; t <= k; ++t) {
        hull.clear();
        ptr = 0;
        for(int i = 1; i <= n; ++i) {
            add(*new line(-2 * l[i], sq(l[i]) + dp[i-1][t-1] - val[i]));
            Min(dp[i][t], sq(r[i] + 1) + get(r[i] + 1));
        }
    }
    return *min_element(dp[n] + 1, dp[n] + 1 + k);
}

Compilation message (stderr)

aliens.cpp: In function 'long long int get(int)':
aliens.cpp:83:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     while(ptr + 1 < hull.size() && hull[ptr].get(x) >= hull[ptr + 1].get(x))
           ~~~~~~~~^~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 12 / 12
• Subtask 3: 9 / 9
• Subtask 4: 0 / 16
• Subtask 5: 0 / 19
• Subtask 6: 0 / 40